Solved Installing new power supply and Video Card

I have a HP Pavilion p6674y Phenom II X4 820(2.8GHz) 6GB DDR3 1TB HDD Capacity ATI Radeon HD 4200 Windows 7 Home Premium 64-bit. I bought a GS Series™ GS800 — 80 PLUS® Bronze Certified Power Supply. I installed it, hooked up the cable and everything but when I try to power it up, the power supply just blinks once, then goes off. It never fully goes on so I can't power up my CPU. What might be the problem with it?

A CPU is a chip that fits in a socket on the motherboard. I think you mean you can't power up your computer.

I'm sure no one here recommended the GS800. It's a great PSU but it's way overpriced, plus you certainly don't need 800W for your system. Why did you install it - was there a problem with the old one or do you plan to do a major upgrade? Are you sure the main 24-pin plug and 4-pin ATX12V are both connected? Did you do anything else to your system other than install a new PSU? Did you mess with the CPU heatsink/fan?

Oh I forgot to mention the reason I installed the 800W. I upgraded my Video card. And I installed GEForce GTX 660 Ti. And I needed a minimum of 500W to be able to use it that's why I upgraded my power supply. So far I rechecked everything I did. On the original power supply it had, there was a connector for the motherboard fan power which has (2 row) 4 pins. And this is the thing I notice the difference between the 250W power supply and the new 800W supply I bought. The 250 W, the 20 pin ATX cable connector that connects to the motherboard is the only one that is connected there. There's another connector that is 4 pin that connects to the fan power on the mother board. On the other hand, the 800 W, has 1 ATX cable (24- pin), and the 4 pin can be detach. This is where i'm confuse, I notice that you can attach the 4 pin to the ATX cable and it can connect on the motherboard main power socket. But the 800 W power supply does not have the (2 row) 4 pins connector that connects to the fan power socket. I tried to detach the ATX cable 20 pins on the motherboard mainpower socket and the detachable 4 pin on the fan power socket. But when I turned on the Computer, the power supply would just light up in a sec then turns off. So I took off the detachable 4 pin from the fan power, attached it on the 20 pin ATX cable and plugged it on the 24 pin socket on the motherboard. Once again, I tried to power it up again, this time the power supply is on BUT the drives won't work? Cause there's a light on the motherboard, so I concluded the drives isn't powered? I checked everything and the peripheral cables are connected to the hard drive and CD/DVD/card reader sockets. So I don't know whats the problem..

Notice in the picture that just to the right of the silver heatsink, above the CPU socket, is a 4-pin socket rotated 45 degrees. That's where the 4-pin ATX12V plug connects. The ATX12V plug powers the CPU (processor).

The main ATX connector is just below the memory slots. It's a 24-pin connector so make sure you do NOT separate the 4-pin plug from the 20-pin plug. That extra 4-pin plug supplies voltage to the PCIe x16 slot for your video card. Plus your video card requires two 6-pin PCIe plugs.

Thanks for the page about the plugs. Now I can finally better explain the problem that I think is the reason why its not working. So you said the extra 4 - pin plug supplies voltage to the PCIe x16 slot for the video card. The 800W has that which is not a problem. The problem is the 800 W does not have the 4 - pin ATX12V plug that powers the CPU. That's what the 800W does not have.. for some reason.

And I have no idea what the "connector for the motherboard fan power which has (2 row) 4 pins" is that you're talking about. Where are the board are you talking about? Go back to the link at the top of my last response, then scroll down to the drawing of the board (not the pic). The case cooling fan connects to SYS_FAN & the CPU cooling fan connects to CPU_FAN. If you connected a power plug to something you shouldn't have, you have have fried something.

"The problem is the 800 W does not have the 4 - pin ATX12V plug that powers the CPU"

Yes it does! ALL modern PSUs have it because ALL modern boards & CPUs require it. I just had a look at your PSU specs. The GS800 has an 8-Pin EPS/ATX12V CPU plug. Look at the pics at the Playtool link. Find that plug & connect it to the board. And don't force it - all plugs are "keyed" so that they can only be plugged in one way.

EPS12V cable. Alright found it. It is detachable, so I only need to connect one or the other and I assumed only one of it works. And I'm sorry I kept calling the computer a CPU, I do know what a CPU is, I just kept using the wrong term to call the computer tower a CPU.

I think there's something you need to know. I mistakenly thought the 4 pin on the ATX main power cable was the ATX12V CPU plug. So I put the 4 pin ATX main power cable on the CPU plug and 20 pin ATX main power cable on the main power socket. Seeing it didn't work, I explored the cables on the power supply and saw the 8 Pin EPS/ATX12V plug and I detached it, and put it on the CPU plug. ANd it didn't work too. Does that mean I fried up something..?

Okay I tried it. Same result. THe power button is suppose on the computer is suppose to light on, which it didn't. Idk whats the problem now. I plugged the monitor on the video card, and the power supply on. The cpu fan was working, and Fan too that blows the hot air out of the computer, I'm guessing? Is that the SYS fan? Anyways, the thing that isn't working that is suppose to is the light on the power button, and the Drive. I'm guessing the drive is the one that isn't working.. WHat do you think?

Since you changed out your power supply, added a video card, and experimented with incorrect plugs, it will be difficult to tell what the problem is. If the motherboard has onboard video, remove the video card and try it without the card to eliminate one or more possible issues and see if that helps you figure it out. If that does not help, you may just want to take it to a pro, tell him(her) everything you have done, and have the computer gone over by someone who is equipped to find the problem(s). Since you will be paying based on the time it will take to fix it, make sure you tell them everything so they know where to look first and do not have to look in the wrong places or retest things already tested.

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